High-Q inductive elements

ABSTRACT

A first insulator is formed on a base layer. A first conductor is formed on the first insulator. The first conductor is patterned. A second insulator is formed over the first insulator. A via hole is formed in the second insulator and is electrically coupled to the first conductor through the via hole. A second conductor is formed on the second insulator, and is electrically coupled to the first conductor by the via hole. The second conductor is patterned. A cavity is formed under the second conductor, and in the first and second insulators.

RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.09/069,346, filed Apr. 29, 1998, now U.S. Pat. No. 6,025,261, grantedFeb. 15, 2000, entitled “Buried Conductors,” hereby incorporated byreference, contemporaneously filed with this application.

FIELD OF THE INVENTION

The present invention relates generally to integrated circuits, and morespecifically to electrical components of integrated circuits.

BACKGROUND OF THE INVENTION

Analog integrated circuits (ICs) are now being extensively used, forexample, in wireless radio frequency (RF) applications such as cellulartelephones where high frequencies are encountered. Many analog ICsinclude inductive elements, such as inductors, formed by a conductor.Inductive elements with a relatively high quality (Q) factor, or lowloss, are preferably used in analog ICs. As a result, the analogintegrated circuits have superior performance, including selectivity,noise figure, and efficiency. Relatively high Q inductors have beenformed on insulating bulk semiconductors, such as gallium arsenide.

Most integrated circuits, however, are formed on silicon. In comparisonto gallium arsenide ICs, silicon ICs can be fabricated relativelyinexpensively. Also, analog and digital circuits may be readily combinedon silicon ICs. However, unlike gallium arsenide, silicon is aconductive bulk semiconductor. As a result, conventional inductiveelements formed on silicon are relatively lossy, and thus haverelatively low Q factors. For example, Q factors of 3 to 8 are reportedfor inductors fabricated on silicon in Nguyen et al., “Si IC-compatibleinductors and LC Passive Filters,” IEEE Journal of Solid-State Circuits,vol. 25, no. 4, p. 1028-1031, 1990, herein incorporated by reference.

An inductor formed on an IC 101 may be a conventional rectangular spiralinductor 103, as illustrated in FIG. 1A. The conventional rectangularspiral inductor 103 includes substantially parallel conductive branches121 that are mutually coupled to increase the rectangular spiralinductor's 103 effective inductance.

The conventional rectangular spiral inductor 103 is formed in thefollowing manner. A first conductor 109 is patterned on the IC 101.Then, an insulator, such as resist, defining the location of air bridges105, is patterned on the IC 101. Next, a second conductor 107 ispatterned on the IC 101. However, where an air bridge 105 is to beformed, the insulator separates the first and second conductors 107,109. Finally, conventional air bridges 105 are formed by removing theinsulator.

Conventional air bridges 105, in this example, permit the two conductors107, 109 to cross one another, without making electrical contact, asillustrated in FIG. 1B. Conventional air bridges 105 are formed bysubstantially perpendicular conductors 107, 109 to diminish undesiredmagnetic coupling between the conductors 107, 109. Further, relativelylow-dielectric-constant air typically separates the conductors 107, 109to diminish undesired capacitive coupling between the conductors 107,109.

FIG. 1C illustrates a prior art first order lumped element electricalmodel of the rectangular spiral inductor 103 that describes theelectrical characteristics of the rectangular spiral inductor 103 belowits self-resonant frequency. The self resonant frequency is the maximumfrequency at which the rectangular spiral inductor 103 acts as aninductor. Above the self resonant frequency, for example, therectangular spiral inductor may exhibit capacitive characteristics.

L is the effective inductance of the rectangular spiral inductor 103.The effective inductance represents the sum of both self and mutualinductances of the branches 121. The inductance, L, of the rectangularspiral inductor 103 is determined by (1) the length of the branches 121,(2) the spacing between the branches 121, and (3) the number of branches121, or turns.

The other model elements are parasitics that result from the physicalimplementation of the rectangular spiral inductor 103. R_(DC) andR_(SKIN EFFECT) are respectively the lumped element equivalent DC andskin effect resistances of the conductors 107, 109. R_(DC) is determinedby the cross-sectional area, length and resistivity of the conductors107, 109. R_(SKIN EFFECT) is determined by the thickness of theconductors 107, 109. C_(S) is a lumped element equivalent capacitancerepresenting the interwinding capacitances between the parallelconductive branches 121. C_(S) is determined by both the distancebetween adjacent branches 121, and the dielectric constant of thematerial proximate to those adjacent branches 121. The C_(pS) are lumpedelement equivalent capacitances representing capacitances between theconductors 107, 109 and a ground plane under the IC 101 on which therectangular spiral inductor 103 is formed. The C_(pS) correspond to thewidth of the conductors 107, 109, and the thickness and dielectricconstant of the material between the conductors 107, 109 and the groundplane. R_(SUBSTRATE) is a lumped element equivalent resistancecorresponding to substrate losses. The Q factor and self-resonantfrequency of the rectangular spiral inductor 103 are a function of thereactances and resistances described by the electrical model of FIG. 1C.

To increase its Q factor, resistances and/or capacitances of therectangular spiral inductor 103 should be reduced. One technique forreducing the Q factor of the inductor is disclosed in J. N. Burghartz etal., “Integrated RF and Microwave Components in BiCMOS Technology,” IEEETrans. Electron Devices, vol. 43, no. 9, pp. 1559-1570, 1996 (hereinafter the “Burghartz Article”), herein incorporated by reference. TheBurghartz Article discloses inductors, on silicon ICs, whose conductorsare displaced above the silicon, and are encased in oxide. Theseinductors have Q factors exceeding 10. The higher Q factors arise, inpart, because the inductors, disclosed in the Burghartz Article, haverelatively lower values of C_(p) because the conductors are fartherdisplaced from the IC ground plane by the oxide.

Further, the inductors disclosed in the Burghartz Article require acomplex five-level metal silicon technology that is more complicatedthan conventional two- to four-level metal silicon technologies.Therefore, there is a need for inductors having relatively high Qfactors that can be formed with conventional silicon technologies.

SUMMARY OF THE INVENTION

The present invention provides a method of forming air bridges, on asubstrate or an integrated circuit, which may be used to form inductorsand other devices. A first insulator is formed on a base layer. A firstconductor is formed on the first insulator. The first conductor ispatterned. A second insulator is formed over the first insulator. A viahole is formed in the second insulator. A second conductor is formed onthe second insulator, and is electrically coupled to the first conductorby the via hole. The second conductor is patterned. A cavity is formedunder the second conductor, and in the first and second insulators. Inone embodiment, the first and second conductors form air bridges.

In another embodiment, a support structure is formed during the step offorming the cavity. In yet another embodiment, a conductive pad isformed over the support structure during the step of patterning thesecond conductor.

In a further embodiment, the present invention provides an air bridge orinductive element on a substrate or integrated circuit. A firstinsulator is formed on a base layer. A first conductor is formed andpatterned on the first insulator. A second insulator is formed on thefirst insulator. A via hole is formed in the second insulator. A maskinglayer is developed on the integrated circuit. A cavity, defined by thedeveloped masking layer, is formed in the first and second insulators.The cavity is filled with a polymer. The integrated circuit is cleaned.A second conductor is formed on the polymer, and coupled to the firstconductor by the via hole. The second conductor is patterned. In yet afurther embodiment, the cavity is filled with a polymer that is foam.

In yet a further embodiment, the inductive element includes a second viahole in the support structure that couples the first and secondconductors. In another embodiment, the cavity is filled with a polymer.In yet a further embodiment, the the polymer is a foam.

In another embodiment, an inductive element on a substrate, or anintegrated circuit, comprises a base layer. A first conductor is buriedin the base layer. An insulator is formed on the base layer. A secondconductor, having first and second branches that are substantiallyparallel, is formed on the second insulator. A plug, formed in the baselayer, is coupled to the first conductor. A via hole, formed in theinsulator, couples the plug to the second conductor. A cavity, undersecond conductor, is formed in the insulator. A support structure, inthe cavity, props up the second conductor above the base layer.

In yet a further embodiment, an inductive element is formed, on asubstrate or an integrated circuit, with a low dielectric inorganicinsulator. A first insulator is formed on a base layer. A firstconductor is formed on the first insulator. The first conductor ispatterned. A second insulator is formed, over the first insulator, fromthe low dielectric inorganic insulator. A portion of the secondinsulator is oxidized. The oxidized portion of the second insulator isremoved. A via hole is formed in the second insulator. A secondconductor, formed on the second insulator, is coupled to the firstconductor by the via hole. The second conductor is patterned.

It is a benefit of the present invention that the inductive elementsdescribed above have an enhanced Q factor. It is a further advantage ofthe present invention that the inductive elements described above havean enhanced self-resonant frequency. It is yet a further benefit of thepresent invention that the inductive elements described above can beformed in conjunction with standard silicon IC processes.

The inductive elements described above can be incorporated in a receiverand/or a transmitter of a communications systems. As a result, thecommunications system will exhibit higher selectivity and efficiency,and lower noise figure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described with reference to the accompanyingdrawings. In the drawings, like reference numbers indicate identical orfunctionally similar elements. Additionally, the leftmost digit(s) of areference number identifies the drawing in which the reference numberfirst appears.

FIG. 1A illustrates a plan view of a prior art rectangular spiralinductor.

FIG. 1B illustrates a cross-sectional diagram of a prior art air bridge.

FIG. 1C illustrates a prior art first order lumped element electricalmodel of a rectangular spiral inductor.

FIG. 2A illustrates a plan view of an integrated circuit including aninductive element.

FIG. 2B illustrates a cross-sectional diagram of the integrated circuitincluding the inductive element.

FIG. 2C illustrates a cross-sectional diagram of an integrated circuitincluding an inductive element and a via hole in a support structure.

FIG. 3 illustrates a cross-sectional diagram of an integrated circuitincluding an inductive element and a buried conductor.

FIG. 4 illustrates a communications system including an inductiveelement according the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following detailed description of the invention, reference ismade to the accompanying drawings which form a part hereof, and in whichis shown, by way of illustration, specific embodiments in which theinvention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention. Other embodiments may be utilized and structural, logical,and electrical changes may be made without departing from the scope ofthe present invention. The terms base layer, wafer, and substrate usedin the following description include any structure having an exposedsurface with which to form the integrated circuit (IC) structure of theinvention. The term substrate is understood to include semiconductorwafers. The term substrate is also used to refer to semiconductorstructures during processing, and may include other layers that havebeen fabricated thereupon. Base layer, wafer and substrate include dopedand undoped semiconductors, epitaxial semiconductor layers supported bya base semiconductor or insulator, as well as other semiconductorstructures well known to one skilled in the art. A ground plane may layunderneath the base layer, wafer or substrate. The term conductor isunderstood to include semiconductors, and the term insulator is definedto include any material that is less electrically conductive than thematerials referred to as conductors. The following detailed descriptionis, therefore, not to be taken in a limiting sense, and the scope of thepresent invention is defined only by the appended claims, along with thefull scope of equivalents to which such claims are entitled.

This application is related to patent application Ser. No. 09/030,430,entitled “METHODS AND STRUCTURES FOR METAL INTERCONNECTIONS ININTEGRATED CIRCUITS,” hereby incorporated by reference. This applicationis also related to patent application Ser. No. 08/892,114, entitled“METHOD OF FORMING INSULATING MATERIAL FOR AN INTEGRATED CIRCUIT ANDINTEGRATED CIRCUITS RESULTING FROM SAME,” hereby incorporated byreference. This application is also related to patent application Ser.No. 08/954,450, entitled “METHOD AND SUPPORT STRUCTURE FOR AIR BRIDGEWIRING OF AN INTEGRATED CIRCUIT,” hereby incorporated by reference. Thisapplication is also related to patent application Ser. No. 08/347,673,entitled “ALUMINUM BASED ALLOY BRIDGE STRUCTURE AND METHOD OF FORMINGSAME,” hereby incorporated by reference.

FIG. 2A illustrates a plan view of one embodiment of the presentinvention, an inductive element 203, specifically a rectangular spiralinductor, formed on an integrated circuit (IC) 201. The rectangularspiral inductor is formed by air bridges 205 propped up by supportstructures 215, to diminish undesired capacitive coupling to a groundplane beneath the IC 201. Substantially parallel conductive branches ofthe spiral inductors are formed by air bridges. FIG. 2B illustrates across-sectional view of the inductive element 203. The inductive element203 can be formed in conjunction with standard silicon processes, forexample using only two conductor levels, utilizing the techniquesdescribed below.

In one embodiment, the inductive element 203 is formed in the followingmanner. A first insulator 206 is formed on a base layer 204. In oneembodiment, the first insulator 206 and base layer 204 are respectivelyan oxide, such as silicon dioxide, and a semiconductor, such as silicon.

Then, a first conductor 209 is formed on the first insulator 206. In oneembodiment, the first conductor 209 is an aluminum alloy. The firstconductor 209 is then patterned to form interconnects to the terminalsof the inductive element 203.

Next, a second insulator 210 is formed over the first insulator 206. Inone embodiment, the second insulator 210 may be an oxide, such assilicon dioxide. Then, via holes 211 are formed in the second insulator210. The via holes 211 are filled with a conductor such as an aluminumalloy.

The integrated circuit 201, including the second insulator 210, issubsequently planarized, for example by chemical-mechanicalplanarization (CMP). Next, a second conductor 207, substantiallydefining the inductive element 203, is formed and patterned on theintegrated circuit 201. In one embodiment, the second conductor 207 isan aluminum alloy. The second conductor 207 is electrically coupled tothe first conductor 209 by the via holes 211.

In one embodiment, the unterminated end of the second conductor 207,proximate to the center of the inductive element 203, is electricallycoupled to the first conductor 209 by a via hole 212 in a supportstructure 215, as illustrated in FIG. 2C. In such an embodiment, thefirst conductor 209 extends into a support structure 215. Alternatively,the via hole 212 in the support structure 215 is not required when asupport structure 215 is formed with a conductive core and insulatingsheath in a manner known to those skilled in the art. In either case,the first conductor 209 is formed at a different height in the cavity213, and therefore does not directly make electrical contact with thesecond conductor 207.

A cavity 213 under the second conductor 209 is then formed bydirectionally etching the first and second insulators 206, 210. In oneembodiment, the directional etching is performed by reactive ionetching. Either the second conductor 207 or a separate masking layer 233formed on the integrated circuit 201 may be used to define the crosssection of the cavity 213, and the support structures 215 for proppingup the first and second conductors 207, 209. Subsequently, in oneembodiment, an anisotropic etch is used to remove undesired first andsecond insulator 206, 210 in the cavity from under the second conductor207, while not substantially diminishing the support structures 215.

Because the first and second conductors 207, 209 are substantiallyseparated from the base layer 204 and the underlying ground plane by arelatively low-dielectric-constant insulator, air, the C_(pS), of FIG.1C, are reduced. Additionally, because the substantially perpendicularbranches of the inductive element 203 are capacitively coupled throughair, instead of the oxide or silicon, the C_(S), of FIG. 1C, is alsoreduced. As a result, the Q factor of the inductive element 203 isincreased. Further, the self-resonant frequency of the inductive element203 is also increased.

In another embodiment of the present invention, conductive pads 231 canbe formed during the patterning of the second conductor 207. Theconductive pads 231 are formed from the second conductor 207. Theconductive pads 231 have a width greater than the width of the secondconductor 207 so that the conductive pads 231 have a relatively largesurface area that covers the support structures 215. As a result, theconductive pads 231 prevent the anisotropic etch from removingsubstantially all of the support structures 215 formed beneath theconductive pads 231. The actual size of the support structure 215 is afunction of the thickness of the insulators 206, 210, and various etchparameters. The conductive pads 231 may be formed at any point along thesecond conductor 207 where a support structure 215 is made, but iscommonly formed where the path of the second conductor 207 changesdirections, such as at the corners as shown in FIG. 2A.

In an alternative embodiment, the cavity 213 and support structures 215may be formed in a manner that does not necessarily require theanisotropic etch described above. Using the initial steps describedabove, through formation of the via holes 211, a masking layer 233 isthen formed on the second insulator 210 of the integrated circuit 201.The masking layer 233 is developed to define the cross-section of acavity 213 and support structures 215. The cavity 213 is formed byisotropically etching the insulator 206, 210 not covered by the maskinglayer 233. The support structures 215 are in the cavity 213.

The cavity 213 and support structures 215 are formed by removing, forexample by etching, some of the first and second insulators 206, 209.Alternatively, in yet another embodiment, the cavity 213 is formedsimultaneously during the formation of the via holes 211 illustrated inFIG. 2B, in a manner know to those skilled in the art.

In one embodiment, an anisotropic etch is used to remove first insulator206 covered by the first conductor 209 in the cavity 213. In such acase, the conductive pads 231, described above, are preferably formedover the support structures 215.

The cavity 213 is then filled, for example, with a polymer 225, such asParylene C, polyimide, or a foam. In one embodiment, the polyimide maybe PMDA-ODA. In another embodiment, the foam may be a foam like thosedisclosed in R. D. Miller et al., “Low Dielectric Constant Polyimidesand Polyimide Nanofoams,” Seventh Meeting of the DuPont Symposium onPolyimides in Microelectronics, Sep. 16-18, 1996, herein incorporated byreference.

The integrated circuit 201, including the polymer 225, is thenplanarized, for example with CMP or etch back techniques until at leastthe via hole 211 is exposed. Then, the integrated circuit 201, includingthe polymer 225 and second insulator 210, is cleaned to permit thesecond conductor 207 to form a low resistivity contact to the via hole211. Next, the second conductor 207, which substantially defines theinductive element 203, is formed and patterned on the integrated circuit201. The second conductor 207 is formed over the cavity 213 and on thesupport structures 215.

In one embodiment, the polymer 225 is then removed from the cavity 213of the integrated circuit 201. As described above, because the first andsecond conductors 207, 209 over the cavity 213 are substantially formedover a low dielectric insulator, such as air or the polymer 225, theinductive element 203 has both an enhanced Q factor and self-resonantfrequency.

In yet a further embodiment, the first conductor 209 and secondinsulator 210 can be replaced with a conductor buried in the base layer304, otherwise known as a buried conductor 364, as illustrated in FIG.3. In FIG. 3, base layer 304 actually comprises a series of layers 360,362, 364, and 368. Buried conductors 364 facilitate increased IC 201density. In one embodiment, the buried conductor 364 is positionedbetween two buried insulators 362, such as oxides. In one embodiment,the buried conductor 364 is tungsten. In this embodiment, the buriedinsulators 362 separate the buried conductor 364 from first and secondsemiconductor layers 360, 368, which are respectively N⁺ and P⁻ dopedsilicon. The buried conductor 364 is electrically coupled to the secondconductor 207 through a plug 366, which can also be made from tungsten,and a via hole 211.

In yet another embodiment, an inductive element 203 is formed without acavity 213, diminishing IC 201 processing requirements. A firstinsulator 206 is formed on the base layer 204. A first conductor 209 isformed on the first insulator 206. The first conductor 209 is patterned.A second insulator 210 is formed, over the first insulator 206, from alow dielectric inorganic insulator. The low dielectric inorganicinsulator may be formed from silicon and germanium which are depositedon the integrated circuit 201 at a temperature below the melting pointof the metal used for the first conductor 209. A technique fordepositing silicon and germanium is described by T. J. King, “Depositionand Properties of Low-Pressure Chemical-Vapor Deposited PolycrystallineSilicon-Germanium Films,” Journal of the Electro-Chemical Society,August 1994, pp. 2235-41, which is hereby incorporated by reference.After silicon and germanium deposition is complete, the second insulator210 is oxidized. The oxidized second insulator contains extractablegermanium oxide, which is removed from the second insulator 210. A viahole 211 is formed in the second insulator 210. A second conductor 207is formed on the second insulator 210. The second conductor 207 iscoupled to the first conductor 209 by the via hole 211. The secondconductor 207 is patterned.

This process provides a second insulator 210 that is porous, and has arelatively low dielectric constant. As a result, the effectivedielectric constant of the portion of the IC underlying the secondconductor 207 is reduced, which diminishes C_(p). Thus, the Q factor andthe self-resonant frequency of the inductive element 203 are enhanced.Further, the capacitances of other IC 201 conductors, over the secondinsulator 210, are desirably diminished.

Further, in another embodiment, the foregoing process can be used toform low dielectric support structures 215 in an inductive element 203having a cavity 213. As a result, the effective dielectric constant ofthe support structures 215 is reduced, further diminishing the C_(pS).Thus, the Q factor and the self-resonant frequency of the inductiveelement 203 are enhanced. Further, the capacitances of other IC 201conductors, over the second insulator 210, are desirably diminished.

An inductive element 203 according to the present invention can be usedin a communications system 400, such as a cellular telephone, asillustrated in FIG. 4. Multiple inductive elements 203 may be coupled inseries and/or in parallel to provide a desired inductance value. Thecommunications system 400 includes antennas 406 respectively coupled toa receiver 404 and a transmitter 402. The receiver 404 is coupled to aspeaker 410. The transmitter 402 is coupled to a microphone 408. Thetransmitter 402 and receiver 404 each may include an inductive element203 coupled to a semiconductor device 422, such as a transistor or adiode.

The inductive elements 203 in the communications system 400 enhancereceiver 404 and transmitter 402 performance. The inductive element 203improves the selectivity and noise figure of the receiver 404. Theinductive element 203 improves the efficiency of the transmitter.

CONCLUSION

It is an advantage of the present invention that it enhances the Q andself-resonant frequency of inductive elements 203. It is also a benefitof the present invention that inductive elements 203 can be formed inconjunction with standard silicon IC processes. Furthermore, it is anadditional benefit of the present invention that it provides inductiveelements 203 that can be used in a communications system to improveselectivity, noise figure and efficiency.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reviewing the abovedescription. For example, the inductive elements 203 may be inductors,transformers or auto-transformers. The inductive elements 203 may beformed with conductors 207, 209, 364 having different elements or alloyswhich include aluminum, titanium, copper, gold, silver, or combinationsthereof. Also, the inductive elements 203 may have a variety of shapes,which include, but are not limited to, rectangles, octagonals andspirals. Furthermore, the techniques described above can be used to formair bridge structures other than for inductive elements 203. Also, ifthe air bridge structures are sufficiently long, additional supportstructures 215, not shown, can be used to prop up the air bridgestructures. The scope of the invention should, therefore, be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

We claim:
 1. A communications device, comprising: a transmitter,including: a semiconductor device, and an inductive element, operativelycoupled to the semiconductor device, including: a base layer, a firstinsulator formed on the base layer, a first conductor formed on thefirst insulator, a second insulator formed on the first insulator, asecond conductor, having first and second branches that aresubstantially parallel, formed on the second insulator, a via in thesecond insulator coupling the first and second conductors, an insulatorcavity, under the second conductor, in the first and second insulators,and a support structure, in the insulator cavity, which supports thesecond conductor above the base layer.
 2. The communications device ofclaim 1, wherein a second via in the support structure of the inductiveelement couples the first and second conductors.
 3. The communicationsdevice of claim 1, wherein the insulator cavity is filled with apolymer.
 4. The communications device of claim 3, wherein the polymer isa foam.
 5. The communications device of claim 1, wherein the secondconductor of the inductive element further comprises a conductive padthat covers the support structure.
 6. A communications device,comprising: a transmitter, including: a semiconductor device, and aninductive element, operatively coupled to the semiconductor device,including: a base layer, a first conductor buried in the base layer, aninsulator formed on the base layer, a second conductor, having first andsecond branches that are substantially parallel, formed on the secondinsulator, a plug, in the base layer, coupled to the first conductor, avia in the insulator coupling the plug to the second conductor, aninsulator cavity, under the second conductor, in the insulator, and asupport structure, in the insulator cavity, which supports the secondconductor above the base layer.
 7. The communications device of claim 6,wherein the first conductor of the inductive element is positionedbetween two buried insulators.
 8. The communications device of claim 6,further comprising a second via in the support structure of theinductive element that couples the first and second conductors.
 9. Thecommunications device of claim 6, wherein the insulator cavity is filledwith a polymer.
 10. The communications device of claim 9, wherein thepolymer is a foam.
 11. The communications device of claim 6, wherein thesecond conductor of the inductive element further comprises a conductivepad that covers the support structure.
 12. A communications device,comprising: a receiver including: a semiconductor device, and aninductive element, operatively coupled to the semiconductor device,including: a base layer, a first insulator formed on the base layer, afirst conductor formed on the first insulator, a second insulator formedon the first insulator, a second conductor, having first and secondbranches that are substantially parallel, formed on the secondinsulator, a via in the second insulator coupling the first and secondconductors, an insulator cavity, under the second conductor, in thefirst and second insulators, and a support structure, in the insulatorcavity, which supports the second conductor above the base layer. 13.The communications device of claim 12, wherein a second via in thesupport structure of the inductive element couples the first and secondconductors.
 14. The communications device of claim 12, wherein theinsulator cavity is filled with a polymer.
 15. The communications deviceof claim 14, wherein the polymer is a foam.
 16. The communicationsdevice of claim 12, wherein the second conductor of the inductiveelement further comprises a conductive pad that covers the supportstructure.
 17. A communications device, comprising: a receiver,including: a semiconductor device, and an inductive element, operativelycoupled to the semiconductor device, including: a base layer, a firstconductor buried in the base layer, an insulator formed on the baselayer, a second conductor, having first and second branches that aresubstantially parallel, formed on the second insulator, a plug, in thebase layer, coupled to the first conductor, a via in the insulatorcoupling the plug to the second conductor, an insulator cavity, underthe second conductor, in the insulator, and a support structure, in theinsulator cavity, which supports the second conductor above the baselayer.
 18. The communications device of claim 17, wherein the firstconductor of the inductive element is positioned between two buriedinsulators.
 19. The communications device of claim 17, furthercomprising a second via in the support structure of the inductiveelement that couples the first and second conductors.
 20. Thecommunications device of claim 17, wherein the insulator cavity isfilled with a polymer.
 21. The communications device of claim 20,wherein the polymer is a foam.
 22. The communications device of claim17, wherein the second conductor of the inductive element furthercomprises a conductive pad that covers the support structure.
 23. Acommunications device, comprising: a transmitter, including: asemiconductor device, and an inductive element, operatively coupled tothe semiconductor device, including: a first insulator on a base layer;a first conductor on the first insulator; a second insulator, formedover the first insulator, from a low dielectric inorganic insulator; avia in the second insulator; and a second conductor, formed on thesecond insulator, that is coupled to the first conductor by the via; andwherein the first and second conductors form substantially parallelbranches.
 24. The communications device of claim 23, wherein the secondinsulator comprises porous silicon.
 25. A communications device,comprising: a receiver, including: a semiconductor device, and aninductive element, operatively coupled to the semiconductor device,including: a first insulator on a base layer; a first conductor on thefirst insulator; a second insulator, formed over the first insulator,from a low dielectric inorganic insulator; a via in the secondinsulator; and a second conductor, formed on the second insulator, thatis coupled to the first conductor by the via; and wherein the first andsecond conductors form substantially parallel branches.
 26. Thecommunications device of claim 25, wherein the second insulatorcomprises porous silicon.
 27. A communications system, comprising: areceiver, and a transmitter, wherein at least one of the receiver andthe transmitter includes: a semiconductor device, and an inductiveelement, operatively coupled to the semiconductor device, including: abase layer, a first insulator formed on the base layer, a firstconductor formed on the first insulator, a second insulator formed onthe first insulator, a second conductor, having first and secondbranches that are substantially parallel, formed on the secondinsulator, a via in the second insulator coupling the first and secondconductors, an insulator cavity, under the second conductor, in thefirst and second insulators, and a support structure, in the insulatorcavity, which supports the second conductor above the base layer.
 28. Acommunications system, comprising: a receiver, and a transmitter,wherein both the receiver and the transmitter include: a semiconductordevice, and an inductive element, operatively coupled to thesemiconductor device, including: a base layer, a first insulator formedon the base layer, a first conductor formed on the first insulator, asecond insulator formed on the first insulator, a second conductor,having first and second branches that are substantially parallel, formedon the second insulator, a via in the second insulator coupling thefirst and second conductors, an insulator cavity, under the secondconductor, in the first and second insulators, and a support structure,in the insulator cavity, which supports the second conductor above thebase layer.
 29. A communication system, comprising: a receiver, and atransmitter, wherein at least one of the receiver and the transmitterincludes: a semiconductor device, and an inductive element, operativelycoupled to the semiconductor device, including: a base layer, a firstconductor buried in the base layer, an insulator formed on the baselayer, a second conductor, having first and second branches that aresubstantially parallel, formed on the second insulator, a plug, in thebase layer, coupled to the first conductor, a via in the insulatorcoupling the plug to the second conductor, an insulator cavity, underthe second conductor, in the insulator, and a support structure, in theinsulator cavity, which supports the second conductor above the baselayer.
 30. A communications system, comprising: a receiver, and atransmitter, wherein both the receiver and the transmitter include: asemiconductor device, and an inductive element, operatively coupled tothe semiconductor device, including: a base layer, a first conductorburied in the base layer, an insulator formed on the base layer, asecond conductor, having first and second branches that aresubstantially parallel, formed on the second insulator, a plug, in thebase layer, coupled to the first conductor, a via in the insulatorcoupling the plug to the second conductor, an insulator cavity, underthe second conductor, in the insulator, and a support structure, in theinsulator cavity, which supports the second conductor above the baselayer.
 31. A communications system, comprising: a receiver, and atransmitter, wherein at least one of the receiver and the transmitterincludes: a semiconductor device, and an inductive element, operativelycoupled to the semiconductor device, including: a base layer, a firstinsulator formed on the base layer, a first conductor formed on thefirst insulator, a second insulator formed on the first insulator, asecond conductor, having first and second branches that aresubstantially parallel, formed on the second insulator, a via in thesecond insulator coupling the first and second conductors, an insulatorcavity, under the second conductor, in the first and second insulators,and a support structure, in the insulator cavity, which supports thesecond conductor above the base layer.
 32. A communications system,comprising: a receiver, and a transmitter, wherein both the receiver andthe transmitter include: a semiconductor device, and an inductiveelement, operatively coupled to the semiconductor device, including: abase layer, a first insulator formed on the base layer, a firstconductor formed on the first insulator, a second insulator formed onthe first insulator, a second conductor, having first and secondbranches that are substantially parallel, formed on the secondinsulator, a via in the second insulator coupling the first and secondconductors, an insulator cavity, under the second conductor, in thefirst and second insulators, and a support structure, in the insulatorcavity, which supports the second conductor above the base layer.
 33. Acommunications system, comprising: a receiver; and a transmitter,wherein at least one of the receiver and the transmitter includes: asemiconductor device, and an inductive element, operatively coupled tothe semiconductor device, including: a base layer, a first conductorburied in the base layer, an insulator formed on the base layer, asecond conductor, having first and second branches that aresubstantially parallel, formed on the second insulator, a plug, in thebase layer, coupled to the first conductor, a via in the insulatorcoupling the plug to the second conductor, an insulator cavity, underthe second conductor, in the insulator, and a support structure, in theinsulator cavity, which supports the second conductor above the baselayer.
 34. A communications system, comprising: a receiver; and atransmitter, wherein both the receiver and the transmitter include: asemiconductor device, and an inductive element, operatively coupled tothe semiconductor device, including: a base layer, a first conductorburied in the base layer, an insulator formed on the base layer, asecond conductor, having first and second branches that aresubstantially parallel, formed on the second insulator, a plug, in thebase layer, coupled to the first conductor, a via in the insulatorcoupling the plug to the second conductor, an insulator cavity, underthe second conductor, in the insulator, and a support structure, in theinsulator cavity, which supports the second conductor above the baselayer.
 35. A communications system, comprising: a receiver; and atransmitter, wherein at least one of the receiver and the transmitterincludes: a semiconductor device, and an inductive element, operativelycoupled to the semiconductor device, including: a first insulator on abase layer; a first conductor on the first insulator; a secondinsulator, formed over the first insulator, from a low dielectricinorganic insulator; a via in the second insulator; and a secondconductor, formed on the second insulator, that is coupled to the firstconductor by the via; and wherein the first and second conductors formsubstantially parallel branches.
 36. A communications system,comprising: a receiver; and a transmitter, wherein both the receiver andthe transmitter include: a semiconductor device, and an inductiveelement, operatively coupled to the semiconductor device, including: afirst insulator on a base layer; a first conductor on the firstinsulator; a second insulator, formed over the first insulator, from alow dielectric inorganic insulator; a via in the second insulator; and asecond conductor, formed on the second insulator, that is coupled to thefirst conductor by the via; and wherein the first and second conductorsform substantially parallel branches.
 37. A communications system,comprising: a receiver; and a transmitter, wherein at least one of thereceiver and the transmitter includes: a semiconductor device, and aninductive element, operatively coupled to the semiconductor device,including: a first insulator on a base layer; a first conductor on thefirst insulator; a second insulator, formed over the first insulator,from a low dielectric inorganic insulator; a via in the secondinsulator; and a second conductor, formed on the second insulator, thatis coupled to the first conductor by the via; and wherein the first andsecond conductors form substantially parallel branches.
 38. Acommunications system, comprising: a receiver; and a transmitter,wherein both the receiver and the transmitter include: a semiconductordevice, and an inductive element, operatively coupled to thesemiconductor device, including: a first insulator on a base layer; afirst conductor on the first insulator; a second insulator, formed overthe first insulator, from a low dielectric inorganic insulator; a via inthe second insulator; and a second conductor, formed on the secondinsulator, that is coupled to the first conductor by the via; andwherein the first and second conductors form substantially parallelbranches.